Bug 885585 - Work around Quartz issue where a stroke with a dasharray whose gaps add up to zero does not render. r=vlad,longsonr

gfx/cairo/README

@@ -206,6 +206,8 @@ fix-win32-font-assertion.patch: Bug 838617, fix assertion from bug 717178 that w
 
 xlib-flush-glyphs.patch: bug 839745, flush glyphs when necessary
 
+dasharray-zero-gap.patch: bug 885585, ensure strokes get painted when the gaps in a dash array are all zero length
+
 ==== pixman patches ====
 
 pixman-android-cpu-detect.patch: Add CPU detection support for Android, where we can't reliably access /proc/self/auxv.

gfx/cairo/cairo/src/cairo-quartz-surface.c

@@ -2578,19 +2578,33 @@ _cairo_quartz_surface_stroke_cg (void *abstract_surface,
 	unsigned int max_dashes = style->num_dashes;
 	unsigned int k;
 
-	if (style->num_dashes%2)
-	    max_dashes *= 2;
-	if (max_dashes > STATIC_DASH)
-	    fdash = _cairo_malloc_ab (max_dashes, sizeof (cairo_quartz_float_t));
-	if (fdash == NULL)
-	    return _cairo_error (CAIRO_STATUS_NO_MEMORY);
+	bool set_line_dash = false;
+	if (style->num_dashes % 2 == 0) {
+	    for (k = 1; k < max_dashes; k++) {
+		if (style->dash[k]) {
+		    set_line_dash = true;
+		    break;
+		}
+	    }
+	} else
+	    set_line_dash = true;
 
-	for (k = 0; k < max_dashes; k++)
-	    fdash[k] = (cairo_quartz_float_t) style->dash[k % style->num_dashes];
+	if (set_line_dash) {
+	    if (style->num_dashes%2)
+		max_dashes *= 2;
+	    if (max_dashes > STATIC_DASH)
+		fdash = _cairo_malloc_ab (max_dashes, sizeof (cairo_quartz_float_t));
+	    if (fdash == NULL)
+		return _cairo_error (CAIRO_STATUS_NO_MEMORY);
 
-	CGContextSetLineDash (surface->cgContext, style->dash_offset, fdash, max_dashes);
-	if (fdash != sdash)
-	    free (fdash);
+	    for (k = 0; k < max_dashes; k++)
+		fdash[k] = (cairo_quartz_float_t) style->dash[k % style->num_dashes];
+
+	    CGContextSetLineDash (surface->cgContext, style->dash_offset, fdash, max_dashes);
+	    if (fdash != sdash)
+		free (fdash);
+	} else
+	    CGContextSetLineDash (state.context, 0, NULL, 0);
     } else
 	CGContextSetLineDash (state.context, 0, NULL, 0);
 

gfx/cairo/dasharray-zero-gap.patch

@@ -0,0 +1,60 @@
+diff --git a/gfx/cairo/cairo/src/cairo-quartz-surface.c b/gfx/cairo/cairo/src/cairo-quartz-surface.c
+--- a/gfx/cairo/cairo/src/cairo-quartz-surface.c
++++ b/gfx/cairo/cairo/src/cairo-quartz-surface.c
+@@ -2573,29 +2573,43 @@ static cairo_int_status_t
+ 
+     if (style->dash && style->num_dashes) {
+ #define STATIC_DASH 32
+ 	cairo_quartz_float_t sdash[STATIC_DASH];
+ 	cairo_quartz_float_t *fdash = sdash;
+ 	unsigned int max_dashes = style->num_dashes;
+ 	unsigned int k;
+ 
+-	if (style->num_dashes%2)
+-	    max_dashes *= 2;
+-	if (max_dashes > STATIC_DASH)
+-	    fdash = _cairo_malloc_ab (max_dashes, sizeof (cairo_quartz_float_t));
+-	if (fdash == NULL)
+-	    return _cairo_error (CAIRO_STATUS_NO_MEMORY);
+-
+-	for (k = 0; k < max_dashes; k++)
+-	    fdash[k] = (cairo_quartz_float_t) style->dash[k % style->num_dashes];
+-
+-	CGContextSetLineDash (surface->cgContext, style->dash_offset, fdash, max_dashes);
+-	if (fdash != sdash)
+-	    free (fdash);
++	bool set_line_dash = false;
++	if (style->num_dashes % 2 == 0) {
++	    for (k = 1; k < max_dashes; k++) {
++		if (style->dash[k]) {
++		    set_line_dash = true;
++		    break;
++		}
++	    }
++	} else
++	    set_line_dash = true;
++
++	if (set_line_dash) {
++	    if (style->num_dashes%2)
++		max_dashes *= 2;
++	    if (max_dashes > STATIC_DASH)
++		fdash = _cairo_malloc_ab (max_dashes, sizeof (cairo_quartz_float_t));
++	    if (fdash == NULL)
++		return _cairo_error (CAIRO_STATUS_NO_MEMORY);
++
++	    for (k = 0; k < max_dashes; k++)
++		fdash[k] = (cairo_quartz_float_t) style->dash[k % style->num_dashes];
++
++	    CGContextSetLineDash (surface->cgContext, style->dash_offset, fdash, max_dashes);
++	    if (fdash != sdash)
++		free (fdash);
++	} else
++	    CGContextSetLineDash (state.context, 0, NULL, 0);
+     } else
+ 	CGContextSetLineDash (state.context, 0, NULL, 0);
+ 
+ 
+     _cairo_quartz_cairo_path_to_quartz_context (path, state.context);
+ 
+     _cairo_quartz_cairo_matrix_to_quartz (ctm, &strokeTransform);
+     CGContextConcatCTM (state.context, strokeTransform);

layout/reftests/svg/reftest.list

@@ -309,6 +309,7 @@ pref(svg.text.css-frames.enabled,true) == text-layout-08.svg text-layout-08-ref.
 HTTP(..) == text-scale-02.svg text-scale-02-ref.svg
 HTTP(..) == text-scale-03.svg text-scale-03-ref.svg
 == text-stroke-scaling-01.svg text-stroke-scaling-01-ref.svg
+== stroke-dasharray-01.svg stroke-dasharray-01-ref.svg
 == stroke-dasharray-and-pathLength-01.svg pass.svg
 == stroke-dasharray-and-text-01.svg stroke-dasharray-and-text-01-ref.svg 
 == stroke-linecap-square-w-zero-length-segs-01.svg pass.svg

layout/reftests/svg/stroke-dasharray-01-ref.svg

@@ -0,0 +1,13 @@
+<!--
+     Any copyright is dedicated to the Public Domain.
+     http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<svg xmlns="http://www.w3.org/2000/svg">
+  <title>Reference for a stroke with a dasharray whose gaps add up to 0 still painting</title>
+  <!-- https://bugzilla.mozilla.org/show_bug.cgi?id=885585 -->
+
+  <g fill="none" stroke="black" stroke-width="2">
+    <path d="M 100,100 v 100"/>
+    <path d="M 110,100 h 100"/>
+  </g>
+</svg>

layout/reftests/svg/stroke-dasharray-01.svg

@@ -0,0 +1,13 @@
+<!--
+     Any copyright is dedicated to the Public Domain.
+     http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<svg xmlns="http://www.w3.org/2000/svg">
+  <title>Test for a stroke with a dasharray whose gaps add up to 0 still painting</title>
+  <!-- https://bugzilla.mozilla.org/show_bug.cgi?id=885585 -->
+
+  <g fill="none" stroke="black" stroke-width="2" stroke-dasharray="10 0">
+    <path d="M 100,100 v 100"/>
+    <path d="M 110,100 h 100"/>
+  </g>
+</svg>